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Acute coronary syndromes are due to rupture or erosion of an atherosclerotic coronary artery plaque with superimposed platelet aggregation and coronary thrombosis. Complete thrombotic occlusion of a coronary artery generally causes acute ST-elevation myocardial infarction (STEMI), whereas incomplete occlusion will usually cause some myocardial necrosis (as shown by a rise in a cardiac-specific serum biomarker such as troponin) and is termed ‘non-ST elevation myocardial infarction’ (NSTEMI). When myocardial ischaemia is present without evidence of myocardial necrosis the clinical syndrome is described as unstable angina (UA). Hospital Episodes Statistics data for England suggest that there may be as many as 100 000–150 000 admissions with UA or NSTEMI per year (Green S, Personal communication, 2010). Although very early mortality (first few days) is lower for NSTEMI than for STEMI, over a longer period (6 months) their risk of death is comparable.1
The recently published NICE clinical guideline on the early management of UA and NSTEMI (CG94) examines selected aspects of in-hospital management, including risk assessment and its impact on patient management, antiplatelet and antithrombin therapy, the role of coronary angiography, revascularisation and intra-aortic balloon counterpulsation, testing for myocardial ischaemia and left ventricular function, specialist versus non-specialist care, rehabilitation and discharge planning. Detailed discussion of the evidence for the guideline can be found in the full version (http://guidance.nice.org.uk/CG94/Guidance/pdf/English, accessed August 2010), and this article summarises the most important conclusions. CG94 assumes that a firm diagnosis of UA or NSTEMI has already been established, and the differentiation of cardiac from non-cardiac chest pain is dealt with in separate NICE guidance (http://guidance.nice.org.uk/CG95/Guidance/pdf/English, accessed August 2010).
An appreciation of an individual's risk of an adverse outcome following UA or NSTEMI is important when assessing which treatment strategies are most appropriate. For instance, antithrombotic agents may reduce further ischaemic events, but increase bleeding complications, and this …